1. Technical Field
The present invention relates to a cryopump, a cold trap, and a vacuum evacuation apparatus.
2. Description of Related Art
A cryopump is a vacuum pump that captures and pumps gas molecules by condensing or adsorbing molecules on a cryopanel cooled to an extremely low temperature. A cryopump is generally used to achieve a clean vacuum environment required in a semiconductor circuit manufacturing process.
For example, Japanese Patent Application Publication No. S60-8481 describes a cryopump in which a thin film made of a fluorine-based resin or another resin is formed on the outer surfaces of the baffle and other member to be housed in the pump case of the cryopump.
In a vacuum process, there are sometimes the cases where supply of a process gas to a vacuum chamber and stop of the supply thereof are repeated. For example, in sputtering, a thin film is typically formed on a substrate by supplying a process gas at a preset flow rate and for a preset period of time. After the sputtering process is ended, the supply of a process gas is stopped to carry out supplementary works, such as exchange of the processed substrate for a new substrate to be processed. It is considered to be necessary that the vacuum degree of a vacuum chamber is recovered to a desired one for preparing the start of the next sputtering process. It is preferable that the period of time necessary for the recovery is as short as possible in terms of improvement of a throughput.